Paperboard based containers have been known for the better part of the twentieth century. Such paperboard based containers include gable-top, flat-top, and brik-type containers.
The characteristic simplicity of these containers have helped to sustain their popularity as containers for traditional liquid food products such as milk and juice, but in recent years they have also been used for products ranging from ammunition to Epsom salts. Gable-top and brik-type cartons typically start out as carton blanks made of laminated paperboard or similar material having a thermoplastic coating. The carton blanks are provided with a number of creases to facilitate folding and forming the blank into a generally rectangular container.
During decades of development, manufacturers of packaging machines have devised a variety of ways to form, fill and seal these containers. Today, the most prevalent packaging machines for gable-top cartons are adapted to receive the carton blank after it has been side sealed. The process of side sealing opposite vertical edges of the carton blank results in the forming of a polygonal (usually rectangular) sleeve. The sleeve is received on an indexable mandrel wheel, which rotates the sleeve into respective positions where the end of the sleeve extending outwardly from the mandrel is folded and sealed to form the bottom of the carton.
After the carton bottom has been formed, the carton is then removed from the mandrel and transported to a filing station, where the carton is filled with product. Once the carton has been filled, the top of the carton is folded, for example, into the familiar gable top configuration and is sealed, thus completing the packaging process.
One example of a known packaging machine that operates generally in accordance with these principles is described in U.S. Pat. No. 3,789,746 to Martensson et al. Other examples of such known packaging machines are described in U.S. Pat. No. 3,820,303 to Martensson et al., U.S. Pat. No. 4,759,171 to Bruveris et al., and U.S. Pat. No. 4,790,123 to Ljungstrom et al. These patents are incorporated by reference.
The containers that are to be filled and sealed by the packaging machine are indexed therethrough from one processing station to the next. Although a high indexing speed may contribute to the overall throughput performance of the packaging machine, that speed is limited, among other things, by the "sloshing" that occurs as an unsealed but filled container is transported between the various processing stations. The sloshing of the container contents occurs as a result of the abrupt start and stop motion of the indexing. As a result of the sloshing, the container contents may splash into the sealing regions at the top of the carton and compromise the integrity of a subsequent sealing operation. Additionally, the container contents may splash into the interior of the packaging machine and thus degrade the performance of the machine, for example, by imposing frequent cleaning and maintenance requirements.
Additional transportation difficulties arise when the container contents or the container interior are sensitive to contaminants. This is particularly true of the contents and/or interior of generally aseptic packages. In such instances, the container contents may become contaminated as the unsealed but filled container is indexed from one processing station to the next since the top of the container remains open to the packaging machine environment during the transportation. Similarly, if the container has been rendered generally aseptic prior to filling, maintaining the interior of the unfilled and unsealed container in its aseptic condition during transportation may be difficult.